I am using the software VirtualBox a lot. It is available for all platforms, efficient, robust and most importantly free. However, in the past I already had some problems with upgrading VirtualBox - resulting in undefined behavior in the guest system. Now that my configuration seems to be perfect, I hardly want to change it.
Upgrading the host system from Windows 8 to Windows 8.1 with Update should be no problem then. At least that's what I thought. It turns out that my primary virtual machine did not want to boot. It is an Ubuntu Linux system, that I set up with 2 processors and 4096 MB of my RAM.
Changing the setting to 3068 MB of RAM brought my a little bit closer to running the system again. Now, however, the startup of the system resulted in a crash. There was only a blank screen showing up after GRUB. What I did not realize at this moment is that VirtualBox selected Ubuntu 32-bit as operating system. Even though the Ubuntu label does not really matter, the architecture does.
After a while I realized that there might be connection between these three problems:
- Not being able to boot with greater / equal 4 GB of RAM
- Not having access to the accelerator tab of the VM
- Seeing that VirtualBox picked the 32-bit mode
The main issue now was: How to activate 64-bit? No option was available and trying it over the command line resulted in an error. Turns out Hyper-V is the bad guy in this scenario. Turning off Hyper-V over the Windows features was quite helpful:
Now I was able to access all possible configurations, like picking the right architecture of my guest system.
Also I could go back to using the full amount of RAM and VirtualBox was able to use 2 processors again. This being said, the accelerator tab was active as well.
This finally resolved all my issues and the only thing I am mad about is that VirtualBox did not notify me in the beginning of the required architecture change (64-bit to 32-bit) as is crucial (and all errors have been related to this modification).